Since you are asking at this point, you have probably not met the irregulars yet. (Any verb with the "yo" form irregular, such as decir = digo = di (tú) & no digas)

As for object pronouns with commands. With affirmative commands, they are attached to the verb (as in the first example I gave you) with accent marks on the vowel you want to hear) and in the negative they take the usual position, in front of the conjugated verb.